[Lldb-commits] [PATCH] D88769: [trace] Scaffold "thread trace dump instructions"

[Greg Clayton via Phabricator via lldb-commits]

clayborg requested changes to this revision.
clayborg added inline comments.
This revision now requires changes to proceed.


================
Comment at: lldb/source/Commands/CommandObjectThread.cpp:2231-2240
+  CommandObjectTraceDumpInstructions(CommandInterpreter &interpreter)
+      : CommandObjectIterateOverThreads(
+            interpreter, "thread trace dump instructions",
+            "Dump the traced instructions for one or more threads.  If no "
+            "threads are specified, show the current thread.  Use the "
+            "thread-index \"all\" to see all threads.",
+            nullptr,
----------------
This command does seem hard to abstract over all flavors of trace. Would it be better to have the trace plug-ins vend a command objects for "thread trace dump"? The idea would be something like "hey trace plug-in, do you have any commands you support for the 'thread trace dump' multiword command?". It could say "yes, I have one called 'instructions' and here is the CommandObjectSP


================
Comment at: lldb/source/Commands/CommandObjectThread.cpp:2245
+  Options *GetOptions() override { return &m_options; }
+
+protected:
----------------
We should override the repeat command method here:

```
const char *GetRepeatCommand(Args &current_command_args, uint32_t index) override;
```

This way if you type:
```
(lldb) thread trace dump instruction --offset 0 --count 32
```
And then hit enter, the next command it should run is:
```
(lldb) thread trace dump instruction --offset 32 --count 32
```
That you can keep dumping more instructions by just hitting ENTER.


================
Comment at: lldb/source/Commands/Options.td:1008
 
+let Command = "thread trace dump instructions" in {
+  def thread_trace_dump_instructions_count : Option<"count", "c">, Group<1>,
----------------
Do we add a "--summary" option to do this command so that when this option is specified would dump the number of instructions that any threads from the might have? Like:
```
(lldb) thread trace dump instructions --summary
thread #1 has 4096 instructions
thread #2 has 234 instructions
```


================
Comment at: lldb/source/Commands/Options.td:1017-1020
+    Desc<"The position of the first instruction to print. Defaults to the "
+    "current position. The instructions are indexed in reverse order, which "
+    "means that a start position of 0 refers to the last instruction "
+    "chronologically.">;
----------------
Is there a "current position" that is maintained? Or is the current position where TraceThread currently is stopped?


================
Comment at: lldb/source/Plugins/Process/Trace/ProcessTrace.h:18
+
+class ProcessTrace : public lldb_private::Process {
+public:
----------------
So one issue is how do we eventually deal with debugging a live process that enables tracing. In that case we already have a real process class: ProcessGDBRemote most likely. We should avoid putting anything custom that is required from a process in this ProcessTrace class for when we actually have a real process class already. If we need to add anything, we will need to have virtual functions on the lldb_private::Process class that can call through to the Trace plug-in via its virtual functions as well to implement any functionality we might need.

Is this class solely going to be used for "trace load"?


================
Comment at: lldb/test/API/commands/trace/TestTraceDumpInstructions.py:46
+        self.expect("thread trace dump instructions --count 5 --start-position 10",
+            substrs=['thread #1: tid = 3842849',
+                     'would print 5 instructions from position 10'])
----------------
need to test the repeat command stuff here if we add support for:
```
const char *GetRepeatCommand(Args &current_command_args, uint32_t index) override {
```


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D88769/new/

https://reviews.llvm.org/D88769